Least common multiple is the smallest multiple that both numbers have.
Multiples of 2 (up to 2⋅10): 2, 4, 6, 8, 10, 12, 14, 16, 18, 20
Multiples of 6 (up to 6⋅5): 6, 12, 18, 24, 30
The smallest multiple that both 2 and 6 have is 6